Hi All
As far as I know, IPsec and L2TP (Layer 2 Tunneling Protocol) over IPsec can be used for VPN Connection.Since L2TP doesn’t support any authentication or encryption mechanisms directly, L2TP is usually bundled with IPSec to provide encryption of user and control packets within the L2TP tunnel. Since both of them can reach the same goal of VPN connection for corporate networks, why there is a need for L2TP over IPsec instead of IPsec itself ? Is it related to L2TP VPN software support for mobile devices such as iOS or Android system and desktop OS ?
L2TP has its origins primarily in two older tunnelling protocols for point-to-point communication: Cisco’s Layer 2 Forwarding Protocol (L2F) and Microsoft’s Point-to-Point Tunnelling Protocol (PPTP). As such, these do not have encryption as you mentioned. However, because L2TP is used by operating systems such as Microsoft Windows, it is primarily implemented with the encryption benefits of IPSec.
Really both will work and provide similar characteristics. Pure IPSec with IPSec tunnelling provides a little more efficiency while IPSec/L2TP can carry multiple protocols (other than IP for example). It all depends on the choice of protocol and the architecture of the endpoints.
